Suppression du fichier passé par le hook. Pour trouver le chemin du fichier indiqué dans le hook :
https://github.com/nextcloud/server/blob/master/lib/private/Files/Cache/Cache.php
/**
* get the path of a file on this storage by it's file id
*
* @param int $id the file id of the file or folder to search
* @return string|null the path of the file (relative to the storage) or null if a file with the given id does not exists within this cache
*/
public function getPathById($id) {
$query = $this->getQueryBuilder();
$query->select('path')
->from('filecache')
->whereStorageId()
->whereFileId($id);
$path = $query->execute()->fetchColumn();
return $path === false ? null : $path;
}